2018-02-22T06:34:32ZThe inferior vena caval compression theory of hypotension in obstetric spinal anaesthesia: studies in normal and preeclamptic pregnancy, a literature review and revision of fundamental conceptshttp://hdl.handle.net/10023/1815
Three clinical investigations together with a combined editorial and review of the cardiovascular physiology
of spinal anaesthesia in normal and preeclamptic pregnancy form the basis of a thesis to be submitted for the
degree of Doctor of Medicine at the University of St Andrews. First, the longstanding consensus that spinal
anaesthesia could cause severe hypotension in severe preeclampsia was examined using three approaches.
The doses of ephedrine required to maintain systolic blood pressure above predetermined limits were first
compared in spinal versus epidural anaesthesia. The doses of ephedrine required were then similarly studied
during spinal anaesthesia in preeclamptic versus normal control subjects. The principal outcome of these
studies, that preeclamptic patients were resistant to hypotension after a spinal anaesthetic, was then further
investigated by studying pulse transit time (PTT) changes in normal versus preeclamptic pregnancy. PTT
was explored both as beat-to-beat monitor of cardiovascular function and also as an indicator of changes in
arterial stiffness. The cardiovascular physiology of obstetric spinal anaesthesia was then reviewed in the light
of the three clinical investigations, developments in reproductive vascular biology and the regulation of
venous capacitance. It is argued that the theory of a role for vena caval compression as the single cause of
spinal anaesthetic induced hypotension in obstetrics should be revised.
Full metadata records and copyright statements for publications contained in this portfolio thesis are available at the identifiers listed
2011-01-01T00:00:00ZSharwood-Smith, Geoffrey H.Three clinical investigations together with a combined editorial and review of the cardiovascular physiology
of spinal anaesthesia in normal and preeclamptic pregnancy form the basis of a thesis to be submitted for the
degree of Doctor of Medicine at the University of St Andrews. First, the longstanding consensus that spinal
anaesthesia could cause severe hypotension in severe preeclampsia was examined using three approaches.
The doses of ephedrine required to maintain systolic blood pressure above predetermined limits were first
compared in spinal versus epidural anaesthesia. The doses of ephedrine required were then similarly studied
during spinal anaesthesia in preeclamptic versus normal control subjects. The principal outcome of these
studies, that preeclamptic patients were resistant to hypotension after a spinal anaesthetic, was then further
investigated by studying pulse transit time (PTT) changes in normal versus preeclamptic pregnancy. PTT
was explored both as beat-to-beat monitor of cardiovascular function and also as an indicator of changes in
arterial stiffness. The cardiovascular physiology of obstetric spinal anaesthesia was then reviewed in the light
of the three clinical investigations, developments in reproductive vascular biology and the regulation of
venous capacitance. It is argued that the theory of a role for vena caval compression as the single cause of
spinal anaesthetic induced hypotension in obstetrics should be revised.